Method and apparatus for correcting time in an electronic wristwatch

ABSTRACT

An electronic timepiece having a pulse generator producing a high frequency time standard signal, a divider circuit formed from a plurality of series-connected divider stages for producing low frequency timing signals in response to said time standard signal and a device for displaying time in response to said timing signals, is provided with a correction circuit disposed in said divider circuit. The correction circuit enables the use of a new method and apparatus for providing a correction signal to the divider stages counting seconds to reset the divider stages to zero seconds during use of the watch, to thereby correct the accuracy of the second display.

BACKGROUND OF THE INVENTION

This invention relates generally to electronic timepieces incorporatingdigital displays, and in particular, to a method and apparatus forcorrecting the time displayed by electronic timepieces such aswristwatches. Electronic timepieces such as wristwatches have becomeknown for their high accuracy and it is very common for suchwristwatches to sustain an accuracy rate within plus and minus 30seconds per month. Such accuracy rates will cause watches which includethe display of seconds, a feature incorporated into very accuratetimepieces, to display the wrong time. Normal time setting, such asduring insertion of a new battery, in the timepiece, is generallylimited to setting the hour and minute. Heretofore, the method ofseconds correction during normal use entailed the holding of the secondhand in a waiting position until the correct time was reached and thenreleasing the hand. Such a method required operating a switch two timesand considerable waiting which renders such method less than completelysatisfactory. Moreover, because wristwatches are limited in the spaceprovided for electronic circuitry, correction circuitry which has beenheretofore suggested, has not provided the accuracy and the minimalspace displacement which is necessary in such watches. Accordingly, itis desirable to produce a small sized digital electronic timepiece,particularly a wristwatch which can be corrected by a simple method andapparatus which includes the addition of a correction signal to thecounting circuit of the watch.

SUMMARY OF THE INVENTION

Generally speaking, in accordance with the invention, an electronictimepiece is provided including pulse generator means for generating ahigh frequency time standard signal, divider means formed from aplurality of series-connected divider stages for producing low frequencytiming signals in response to said high frequency time standard signaland representative of present time, and digital display means for thedigital display of time in response to said timing signals. A correctioncircuit is coupled to certain of said divider stages to apply a resetsignal thereto.

A method for correcting the seconds display during normal use of thetimepiece is provided when the seconds display is incorrect within atime period of plus and minus 30 seconds. Upon observing that the actualtime is exactly at a minute indication, an operator provides acorrection signal to certain of the divider stages which correspond tothe display of seconds, the correction signal effecting the reset ofsuch certain divider stages to zero seconds and the restarting thereof.Where the time displayed is slow by 1 to 30 seconds, application of thecorrection signal further effects an advancement of the minute display.

Accordingly, it is an object of the invention to provide a small-sizedelectronic timepiece provided with a digital display and having animproved correction circuit.

Still another object of this invention is to provide an improvedsmall-sized electronic timepiece provided with an improved correctioncircuit and method for utilizing the same.

Still another object of the invention is to provide an improved methodfor correcting small-sized electronic timepieces.

The invention accordingly comprises several steps and the relation ofone or more of such steps with respect to each of the others, and theapparatus embodying features of the construction, combination ofelements and arrangements of parts which are adapted to effect suchsteps, all as exemplified in the following detailed disclosure, and thescope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is had to thefollowing description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a perspective view of an electronic wristwatch constructed inaccordance with the preferred embodiment of the instant invention;

FIG. 2 is a block diagram of the circuitry of the electronic wristwatchillustrated in FIG. 1;

FIG. 3 is a perspective view of the digital display of the electrontimepiece of FIG. 1 illustrating a first mode of correction;

FIG. 4 is a perspective view of the digital display of the electronictimepiece of FIG. 1 illustrating a second mode of correction;

FIG. 5 is a circuit diagram including the correction circuit of theelectronic timepiece of FIG. 1; and

FIG. 6 is a wave diagram corresponding to the circuit of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, an electronic timepiece is illustrated therein andincludes a digital display 5, for displaying the present time in termsof minutes, hours and seconds. The front of the watch further includestime setting switches 6 and 7 which enable setting and correction of thehours and the minutes digits respectively of display 5. Switch 8 is atime correcing switch used in the method and apparatus of the instantinvention.

Referring now to FIGS. 2 and 5, the circuitry of the electronictimepiece of FIG. 1 is illustrated, including a pulse generator 1, whichmay take the form of a quartz crystal oscillator or the like. A highfrequency time standard signal output of pulse generator 1 is applied todivider and distributor circuit 2 which includes a divider chain whichdivides the time standard signal into time keeping signals such ashours, minute, and second signals. The dividers of the divider chainproducing the time keeping signals may be selectively corrected by meansof correction circuit 4 including switches 6, 7 and 8. The instantaneoustime-keeping signals are applied to distributor circuits which placethem in a form for driving the respective digits of digital display 3.

As shown in FIG. 5, the divider chain of divider and distributor circuit2 includes the divider circuits 9 through 15 each of which producesinstantaneous timing signals counted therein for application todistributor circuits 16, 17 and 18 as will hereinafter be discussed. Inthe divider circuit depicted in FIG. 5, divider circuit 9 receives ahigh frequency signal such as would be supplied by the crystaloscillator and produces a 1-second signal having a period of 1 second.The 1-second signal from divider circuit 9 is then applied to a serieschain of divider circuits 10 through 15 which produce timing signals fordisplay. Thus, divider circuit 10 is a 1/10 divider circuit forproducing a 10-second signal; divider circuit 11 is a 1/3 divider forproducing a 1/2 minute signal; divider circuit 12 is a 1/2 divider forproducing a 1-minute signal; divider circuit 13 is a 1/10 divider forproducing a 10-minute signal; divider circuit 14 is a 1/6 dividercircuit for producing a 1-hour signal; and divider circuit 15 is a 1/12divider circuit for producing a 12 hour signal.

Divider circuits 10 through 15 supply instantaneous timing signalscounted therein to distributors 16, 17 and 18 which correspondrespectively to the second, minute and hour digits of the digitaldisplay, divider circuits 10, 11 and 12 being connected to distributor16, divider circuits 13 and 14 being connected to distributor 17 anddivider circuit 15 being connected to distributor 18.

The time correcting circuit 4 includes conventional time settingswitches 23 and 24 which correspond to time setting switches 6 and 7respectively of FIG. 1, and time correcting switch 22 which correspondsto switch 8 of FIG. 1. The time correcting switch 22 is coupled to awaveform shaping circuit 19 which in turn is coupled to divider stages 9through 12. By application of a correction signal to divider circuitstages 9 through 12 by actuation of switch 22, a reset signal issupplied by the wave shaping circuit 19 to the divider stages to therebyreset the divider stages. Time setting switches 23 and 24 are coupled tocontrol circuits 20 and 21 which control circuits shape the waveform ofthe time setting signal from switches 23 and 24 and the output or carrysignal from the next previous divider stage and supply corrected carrysignal to the next subsequent divider stage in response to therespective signals supplied thereto. Thus, control circuit 20 receivesthe carry signal from divider 12 and the correction signal from switch23 and insures that the count of the signal applied to divider 13 isincreased by one for each operation of switch 23 to effect correction ofthe minutes digits of the digital display. Correction of the hoursdigits is effected in a like manner by switch 24 and control circuit 21.Control circuits 20 and 21 are each adapted to produce a positive pulseof short duration for each positive excursion of the signals appliedthereto.

Reference is now made to FIG. 6 in which waveform 25 corresponds to thecorrection signal supplied from wave shaping circuit 19 to the dividerstages 9 through 12; waveform 26 corresponds to the 1-minute signalsupplied from divider circuit 12 to control circuit 20; and, waveform 27corresponds to the output of control circuit 20 in the absence of anysignals applied from time setting switch 23.

Where the error is plus or minus 30 seconds or less, there are twopossible modes of correction using time correction switch 22, dependingon whether the watch is running fast or slow. The first mode where thewatch is fast is illustrated in FIG. 3, where the time before correctionis 10 hours, 59 minutes and 25 seconds. An operator will use a standardreference source for telling time such as a radio, T.V. or telephoneoperator to aid in correcting the time. When the standard reference timeis 10 hours, 59 minutes and 0 second, switch 22 is closed and a resetpulse is generated in wave shaping circuit 19 which is then supplied todivider stages 9 through 12, thus resetting each of said divider stagesto zero. In this case, the reset signal 25 depicted in FIG. 6, isapplied to divider stage 12 during a period (0-30 seconds) that theoutput is already positive so that resetting has no immediate effect onthe output signal 26 of divider circuit 12. The width of the positivepulse of output signal 26 during which switch 22 is operated isincreased since the count of seconds starts again from zero seconds.Thereafter, signal 26 resumes its normal 1-minute period. The next pulseof signal 27 from central circuit 20 is thus retarded by an amountsufficient to permit correction. The application of the reset signal atthe proper time thus corrects the time from 10 hours 59 minutes and 25seconds to 10 hours and 59 minutes and 0 seconds, and immediatelyrestarts the timing signals so as to then provide normal use of thewristwatch.

The second mode of operation for use when the watch is running slow by30 seconds or less is illustrated with reference to FIG. 4. In this modecorrection is effected when the seconds display reads above 30 seconds,at which time output signal 26 from divider stage 12 is negative. If acorrection pulse 25 from wave-form shaping circuit 19 is applied todivider stages 9 through 12 to reset the divider stages during thisperiod, the resetting stage 12 to zero makes the output signal 26positive. The earlier than normal positive excursion of signal 26produces a pulse out of control circuit 20 (in signal 27) to advance theminute display by one. Thus, the watch display as depicted in FIG. 4shows a time of 10 hours 59 minutes and 37 seconds, and upon applicationof a correction signal by an operator corresponding to an 11 o'clockstandards referenc time, the time on the watch will be corrected to 11o'clock and the watch will continue to operate in a normal mode.

It is understood that time correction of a wristwatch in normal use isperformed, and that electronic circuits can be easily produced whichwill consume a minimum of power, yet be miniature enough to be used inthe small space displacement required in an electronic wristwatch. Theuse of C-MOS integrated circuitry will provide low power consumption andthe requisite small size to such wristwatch components.

It will thus be seen that the objects set forth above, among those madeapparent from the preceeding description, are efficiently attained and,since certain changes may be made in carrying out the above method, andin the construction set forth without departing from the spirit andscope of the invention, it is intended that all matter contained in theabove description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:
 1. An electronic timepiece comprising oscillatormeans for producing a high frequency time standard signal, divider meansfor producing low frequency timing signals from said high frequency timestandard signals including a plurality of series-connected dividerstages, certain of said divider stages corresponding to seconds display,means for the digital display of time in response to said timingsignals, said digital display means displaying at least seconds andminutes, said seconds divider stages providing a substantiallysquarewave output signal having a period of 1 minute to the next dividerstage, and correction means for applying a reset signal to said certaindivider stages which correspond to the incorrect time displayed, saidcorrection means being adapted to set the second digital display to zerowithout affecting the minute digital display when said reset signal isapplied to said certain dividers during the first half cycle of saidoutput signal when the seconds digital display means is 30 or less andto set the second digital display to zero and increase the minutedigital display by one when said reset signal is applied to said certaindividers during the second half cycle of said output signal when saidseconds digital display read more than
 30. 2. An electronic timepiece asclaimed in claim 1, wherein said certain divider stages are a 1/6divider stage corresponding to a 1-second display and 1/3 and 1/2divider stages corresponding to a 10-second display.
 3. An electronictimepiece as claimed in claim 2, wherein said correction means includesa wave shaping means for supplying said reset signal to said certaindivider stages in the form of a pulse.
 4. An electronic timepiece asclaimed in claim 3, wherein said correction means includes a manuallyoperated switch means coupled to said wave shaping means, forselectively causing the application of said pulse reset signal to saidcertain divider stages.
 5. An electronic timepiece as claimed in claim4, wherein a second manually operated switch means is coupled to saidnext divider stage to effect correction of the minutes display.
 6. Amethod for correcting errors of minus 30 seconds or less in anelectronic timepiece having oscillator means for producing a highfrequency time standard signal, divider means for producing lowfrequency timing signals from said high frequency time standard signalincluding a plurality of series-connected divider stages, certain ofsaid divider stages .Iadd.including seconds divider stages.Iaddend.producing a square wave timing signal to the next divider stageand means for the digital display of time including at least .[.aseconds and.]. a minutes display in response to said timing signals, themethod comprising the steps of, at the nearest correct minuteindication, in response to the second half cycle of the square wavetiming signals.Iadd., .Iaddend.resetting the .Iadd.seconds.Iaddend.divider stages producing the .Iadd.seconds .Iaddend.timingsignals .[.associated with the digital display of seconds.]. to zero andincreasing the count of the next divider stages producing timing signalsassociated with the digital display of minutes by one.